Distributed architecture wireless RF modem

ABSTRACT

The present invention provides for a wireless radio frequency (“RF”) modem that plugs into a host computer and shares a central processing unit and memory with the host computer, wherein principal modem functions are distributed between the modem and the host computer. In one embodiment, the modem performs RF conversion, and the host computer performs baseband processing and protocol stack control. In another embodiment, the modem performs RF conversion and baseband processing, and the host computer performs protocol stack control.

[0001] This application claims the benefit of U.S. ProvisionalApplication No. 60/224,577 filed Aug. 11, 2000.

FIELD OF THE INVENTION

[0002] The present invention is directed to wireless radio frequencymodems and, more specifically, to detachable wireless radio frequencymodems that share a central processing unit and memory with a hostcomputing device.

BACKGROUND OF THE INVENTION

[0003] Current wireless radio frequency (“RF”) modems that cooperativelyoperate with a host computing device (“host computer”) typicallyinclude: (1) a radio portion, also called an RF front end or an RF head;(2) a modulator/demodulator portion, also called a baseband processingunit or baseband chip; (3) a central processing unit (“CPU”) orprocessor; (4) memory; and (5) an interface. These modem componentscollectively operate during a wireless communications process to receivean electromagnetic RF signal in a receive mode, wherein the RF signalcontains information to be extracted from the received RF signal, and ina transmit mode, wherein the components work collectively to transmit anelectromagnetic RF signal and the RF signal contains the information tobe transmitted. Moreover, during the receive and transmit modes, themodem components collectively operate to perform three principal modemfunctions: RF conversion, baseband processing and protocol stackcontrol.

[0004] Typically during RF conversion, the RF head receives the RFsignal during the receive mode and converts that RF signal into amodulated baseband analog signal and, during the transmit mode, the RFhead converts a modulated baseband analog signal into an RF signal fortransmission. During baseband processing, the baseband processing unitin the receive mode demodulates the modulated baseband analog signal byextracting a plurality of data bits that correspond to the informationbeing received. In the transmit mode, the baseband processing unitgenerates the modulated baseband analog signal for processing by the RFhead.

[0005] As part of the above wireless communications process, data bitsbeing transmitted are wrapped with protocol bits of data to facilitatetransmission, routing, and receiving of the data bits. Likewise, thisprotocol data must be removed to accurately reproduce, in the receivingRF modem, the data that was sent. The adding or stripping of theprotocol bits, also called protocol stack control, is generallyperformed by the processor in the RF modem under the control of aprotocol stack software program stored in the RF modem's memory.Finally, the interface feeds the data bits from the host computer to theRF modem for processing and transmission and feeds to the host computerthe reproduced data bits that were extracted from the RF signal.

[0006] The host computer may typically be a laptop or palmtop computer,a Personnel Digital Assistant (PDA) such as a PALM Pilot or Handspring,a point of sale terminal, or some other computing system. Typicalinterfaces between the wireless RF modem and the host computer areRS-232, USB, Parallel Port, IrDa, PCMCIA, or Compact Flash. However,other interfaces are also used, including a variety of proprietaryinterfaces. Moreover, there are many wireless RF standards that must beconsidered in the design of any wireless RF modem. Some examplesinclude: circuit switched commercial telecommunications standardsincluding AMPS, CDMA (IS95A & B), and GSM; packet switched standardsincluding CDPD, 1XRTT, GPRS, EDGE, and W-CDMA; and proprietary wide areawireless networks such as Metricom, Re-Flex, FLEX, Mobitex, and ARDIS.

[0007] Wireless RF modem use has grown very rapidly during recent yearsand is projected to continue to grow. Whereas in the past, only a fewkinds of host computers were equipped with wireless RF modems, the trendof incorporating such modems is growing, especially with respect towireless RF modems that plug into laptops and PDAs.

[0008] Typically, the detachable wireless RF modems that workcooperatively with host computers perform all of their functions withinternal software and hardware. They rely on the host computers only toprovide data to be transmitted and a receptacle for data received by themodem from the received RF signal. Accordingly, several hardwarecomponents and software functions are typically duplicated in thewireless modem and the host computer. For instance, both the modem andthe host computer typically have a CPU, various types of memory, UARTSfor serial transmission and reception of data, and other subsystems,with both the modem's and the host computer's CPU operatingindependently of each other. Such hardware and software duplicationsresult in the high cost of wireless RF modems.

[0009] Prior art wireless RF modem architectures are thereforeinadequate because they are expensive, consume more power than is neededdue to the redundant hardware, take up more space, and weigh more thannecessary. What is needed is a wireless RF modem that shares certaincomponents resident in its host computer, thereby enabling the hostcomputer to perform some of the modem's principal functions and thuseliminate the need for redundant hardware in the modem.

SUMMARY OF THE INVENTION

[0010] The present invention is directed at addressing theabove-mentioned shortcomings, disadvantages, and problems of the priorart. A preferred embodiment of the present invention provides for adetachable wireless radio frequency (RF) modem constructed tocooperatively operate with a host computing device having a memory, acentral processing unit (“CPU”) for executing a protocol stack softwareprogram stored in the memory, and a baseband processing unit. The RFmodem comprises: an antenna; an RF head coupled to the antenna and aninterface.

[0011] The RF head is configured during a receive mode to receive anelectromagnetic RF signal through the antenna and to convert the RFsignal into a modulated baseband analog signal for baseband processingin the host computing device. The RF head is further configured during atransmit mode to receive a modulated baseband analog signal generated bythe host computing device and to convert the modulated baseband analogsignal into an electromagnetic RF signal to feed to the antenna. Theinterface is coupled to the RF head and configured to physically couplethe RF modem to the host computing device. The interface is alsoconfigured during the receive mode to feed the modulated baseband analogsignal, generated by the RF head, to the host computing device to enablethe baseband processing unit to convert the modulated baseband analogsignal into a plurality of bits of data including protocol data and thento remove the protocol data. The interface is further configured duringthe transmit mode to feed the modulated baseband analog signal,generated by the host computing device, to the RF head.

[0012] Thus, in this embodiment the wireless RF modem performs RFconversion. The baseband processing and the protocol stack controlfunctions are performed by the host computing device.

[0013] Another embodiment of the present invention also provides for anRF modem comprising an antenna, an RF head to perform RF conversion, andan interface. However, the RF head has a predetermined set of operatingcharacteristics, and the RF modem further comprises an RF identification(“RFID”) unit coupled between said RF head and said interface. The RFIDunit generates an identification signal that identifies thecharacteristics of the RF head, and the interface feeds theidentification signal to the host computing device to enable the hostcomputing device to decode the identification signal and determine theRF head's operating characteristics. In response thereto, the hostcomputing device downloads the appropriate software to the basebandprocessing unit and enables the CPU to perform the appropriate protocolstack control in order to configure the entire RF modem according to thedetected type of RF head.

[0014] Another embodiment of the present invention provides for an RFmodem comprising an antenna, an RF head to perform RF conversion, and abaseband processing unit to perform baseband processing. The hostcomputing device performs the protocol stack control. The RFID hardwarecan be added to this embodiment to create yet another embodiment of thepresent invention.

[0015] Another embodiment of the present invention provides for a systemfor providing wireless data communications comprising a detachablewireless RF modem for performing RF conversion, physically coupled to ahost computing device that functions to provide baseband processing andprotocol stack control. This embodiment can be implemented with orwithout the RFID hardware and software.

[0016] Another embodiment of the present invention comprises a systemfor providing wireless data communications comprising a detachablewireless RF modem for performing RF conversion and baseband processing,physically coupled to a host computing device that functions to provideprotocol stack control. This embodiment can be implemented with orwithout the RFID hardware and software.

[0017] Another embodiment of the present invention provides for a methodfor wireless data communications in a system comprising a detachablewireless RF modem having an antenna, an RF head, and an interface,wherein the RF modem is constructed to cooperatively work with and bephysically coupled at the interface to a host computing device, whereinthe host computing device has a memory, a CPU for executing a protocolstack software program stored in the memory, and a baseband processingunit.

[0018] Another embodiment of the present invention comprises a methodfor wireless data communications in a system comprising a detachablewireless RF modem having an antenna, an RF head, a baseband processingunit, and an interface, wherein the RF modem is constructed tocooperatively work with and be physically coupled at the interface to ahost computing device, wherein the host computing device has a memoryand a CPU for executing a protocol stack software program stored in thememory.

[0019] The key objective of the present invention is to provide a lowcost wireless RF modem by distributing the principal modem functionsbetween a wireless RF modem and its host computing device. The advantageof the present invention is the elimination of redundant hardware in theRF modem and the host computing device, thereby enabling the RF modem tohave fewer components and to consume less power during operation.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The forgoing aspects and the attendant advantages of thisinvention will become more readily apparent by reference to thefollowing detailed description, when taken in conjunction with theaccompanying drawings, wherein:

[0021]FIG. 1 is a schematic illustration of a prior art wireless RFmodem that is designed to be plugged into a PCMCIA slot connector withina host computer;

[0022]FIG. 2 is a schematic illustration of a prior art combination ofthe wireless RF modem of FIG. 1 and a host computer with a PCMCIA slotconnector.;

[0023]FIG. 3 is a schematic illustration of a detachable wireless RFmodem in accordance with a preferred embodiment of the presentinvention, wherein the modem has an antenna, an RF head, and aninterface;

[0024]FIG. 4 is a schematic illustration of a host computer designed towork in conjunction with the wireless RF modem of FIG. 3;

[0025]FIG. 5 is a schematic illustration of a detachable wireless RFmodem in accordance with another embodiment of the present invention,wherein the modem has an antenna, an RF head, a baseband processingunit, and an interface and wherein the modem does not perform protocolstack control;

[0026]FIG. 6 is a schematic illustration of a host computer designed towork in conjunction with the wireless RF modem of FIG. 5;

[0027]FIG. 7 is a schematic illustration of a system for wireless datacommunications in accordance with another embodiment of the presentinvention comprising the wireless RF modem of FIG. 3 equipped with anRFID unit and the host computer of FIG. 4 provided with RFID decodingsoftware; and

[0028]FIG. 8 is a flow chart illustrating steps taken by the system ofFIG. 7, wherein the host computer identifies an identification signalemitted by the RFID unit.

DETAILED DESCRIPTION OF THE INVENTION

[0029]FIG. 1 is a schematic illustration of a prior art wireless RFmodem 100 that is designed to be plugged into a PCMCIA slot connectorwithin a host computer. In this representation of prior art RF modem100, Dual Conversion Transceiver 150, High Speed Synthesizer 180, PowerAmplifier 115, Filters 120, and RF Switch 160 comprise an RF head, whichperforms RF conversion. Dual Conversion Transceiver 150 and High SpeedSynthesizer 180 are available from Texas Instruments of Dallas, Tex. RFswitch 160 may be a transmit/receive switch or a duplexer, as requiredby a given air standard.

[0030] Analog Baseband and Codec 125 and Digital Baseband and CPU 170work in conjunction with Flash Memory and SRAM 135 and comprise thebaseband processing unit and the CPU, which performs baseband processingand protocol stack control. Analog Baseband and Codec 125 and DigitalBaseband and CPU 170 are available from Analog Devices of Norwood, Mass.RF modem 100 also includes an Antenna 110, a Clock 190, a PCIC ASIC 130,and a PCMCIA connector 140. The above components of RF modem 100 areelectrically connected as illustrated by the solid lines in FIG. 1between those components.

[0031] RF modem 100 operates as follows. In the receive mode, anelectromagnetic RF signal is received at Antenna 110 which is connectedto RF switch 160. The received RF signal is routed through RF switch 160to Dual Conversion Transceiver 150, which converts the RF signal into amodulated baseband analog signal for baseband processing. DualConversion Transceiver 150 operates using various receive and transmitvariable frequency oscillator signals that are provided by High SpeedSynthesizer 180. The modulated RF signal from Dual ConversionTransceiver 150 is fed to Power Amplifier 115 which also is fed a signalthat controls the power output so that Power Amplifier 115 can deliverrequested power to RF Switch 160. Various filters as required for DualConversion Transceiver 150 are shown as Filters 120. The modulatedbaseband analog signal from Dual Conversion Transceiver 150 is fed intoAnalog Baseband and Codec 125 for proper demodulation to extract databits comprising true data, which is representative of the informationbeing received, protocol bits of data, and any security coding. DigitalBaseband and CPU 170 further processes the received signal by executinga protocol stack software program, to separate the true data from theprotocol data and to remove any security coding. Digital Baseband andCPU 170 then sends the true data through a timing and interface PCICASIC device 130 to PCMCIA connector 140 to be fed to a host computer.Clock 190 provides a system clock to Digital Baseband and CPU 170 andHigh Speed Synthesizer 180. Flash Memory and SRAM 135 provide forprogram storage and variable storage for Digital Baseband and CPU 170,e.g., storing the protocol stack software program.

[0032] In the transmit mode, true data to be transmitted is fed throughPCMCIA Connector 140, through PCIC ASIC 130, to Digital Baseband and CPU170, wherein the true data is wrapped with protocol data and anynecessary security data and sent to Analog Baseband & Codec 125. AnalogBaseband & Codec 125 generates the modulated baseband analog signal andsends it to Dual Conversion Transceiver 150 to generate theelectromagnetic RF signal. The RF signal to be transmitted is thenamplified by Power Amplifier 115 and sent through RF switch 160 toAntenna 110 for transmission. As illustrated in FIG. 1, prior art RFmodem 100 has its own CPU and its own memory, and all modem functionsare performed and controlled by components housed within RF modem 100.

[0033]FIG. 2 is a schematic illustration of a prior art combination ofwireless RF modem 100 of FIG. 1 and a host computer 200 with a PCMCIAslot connector 280. Double arrow 270 indicates an action of insertingand connecting wireless RF modem 100 to host computer 200, such thatPCMCIA slot connector 280 is connected to PCMCIA Connector 140 in RFmodem 100.

[0034] Host computer 200 contains a power source 240, a memory 220 thattypically comprises a ROM, RAM, SRAM, Flash, or other combination ofmemory accessible by a CPU 230. Computer system Input/Output (I/O)circuitry is shown connecting CPU 230 to PCMCIA connector 280. Data tobe sent or received by CPU 230 is communicated to PCMCIA connector 280using standard software drivers for the connection and standard AT Modemcommands. Operator interface 250 can be programmed to displayinformation concerning the operation of the RF modem 100. When RF modem100 is combined with host computer 200, there are several hardwarefunctions that are duplicated, such as the PCMCIA hardware in both themodem and the host, memory in both, a CPU in both, and common softwarein both.

[0035]FIG. 3 is a schematic illustration of a detachable wireless RFmodem 300 in accordance with a preferred embodiment of the presentinvention, wherein RF modem 100 comprises an Antenna 310, an RF head,and an RF to Baseband Interface 375. The RF head comprises RF switch orduplexer 360, Dual Conversion Transceiver 350, High Speed Synthesizer380, Power Amplifier 315, and Filters 320, and performs RF conversion.RF modem 300 can be constructed using standard components. For instance:Dual Conversion Transceiver 350 and High Speed Synthesizer 380 areavailable from Texas Instruments of Dallas, Tex.; and RF to BasebandInterface 375 can be any standard interface that enables RF modem 300 tobe inserted in a conventional way into an available slot in the hostcomputing device, i.e., Interface 375 enables RF modem 300 to bedimensioned to fit within a cradle for a PDA or enables RF modem 300 tobe dimensioned to correspond to a PCMCIA personal computer card. Thus,RF modem 300 can be designed to be housed inside the host computingdevice or it can be connected external to the host computing device.Moreover, the above components of RF modem 300 are electricallyconnected as illustrated by the solid lines in FIG. 3 between thosecomponents.

[0036] RF modem 300 operates as follows. In the receive mode, Antenna310 receives an electromagnetic RF signal and forwards the RF signal toRF Switch 360. RF switch 360 may be a transmit/receive switch or aduplexer as required by the air standard. The received RF signal is thenrouted from RF switch 360 to Dual Conversion Transceiver 350 forconversion into a modulated baseband analog signal. Dual ConversionTransceiver 350 operates using various receive and transmit variablefrequency oscillator signals that are provided by High speed Synthesizer380. Power amplifier 315 is fed the modulated RF signal from DualConversion Transceiver 350 and is fed a signal that controls poweroutput so that Power Amplifier 315 can deliver requested power to RFSwitch 360. The modulated baseband analog signal from Dual ConversionTransceiver 350 is fed through RF to Baseband Interface 375 to a hostcomputer for external baseband processing and protocol stack control.

[0037] In the transmit mode, an externally generated modulated basebandanalog signal is fed into the RF head through RF to Baseband Interface375 and directed to Dual Conversion Transceiver 350 where the modulatedbaseband analog signal is converted to an electromagnetic RF signal. TheRF signal to be transmitted is then amplified by Power Amplifier 315 andsent through RF switch 360 to Antenna 310 for transmission.

[0038] The total component count in FIG. 3 is substantially less thatthe component count of a typical prior art wireless RF modem, asillustrated in FIG. 1. This represents a substantial savings in partscost, assembly, device testing, and size.

[0039]FIG. 4 is a schematic illustration of a host computer 400 designedto work in conjunction with wireless RF modem 300 of FIG. 3. Hostcomputer 400 contains a Power Source 440, a Memory 420, of type ROM,RAM, SRAM, Flash, or some combination of memory types, accessible to CPU430. Computer system I/O circuitry is shown connecting CPU 430 to aclock 490, to an Analog Baseband and Codec 425 and to a power source440. Analog Baseband and Codec 425 performs baseband processing andprotocol stack control and is available, for instance, from AnalogDevices of Norwood, Mass. Data is sent or received through Baseband toRF interface 475 to the RF to Baseband connector 375 in RF modem 300.The above components of host computer 400 are electrically connected asillustrated by the solid lines in FIG. 4 between those components.

[0040] Host computer 400 operates as follows. In the receive mode,Analog Baseband and Codec 425 receives through Baseband to RF Interface475 the modulated baseband analog signal generated by RF Modem 300 andprocesses it for proper demodulation, wherein the modulated signal isconverted to a plurality of data bits including protocol data and anysecurity coding. CPU 430 further processes the received signal byextracting the true data from the protocol data, removing any securitycoding, and sending the true data to a predetermined destination withinhost computer 400. Protocol stack control is performed by CPU 430executing a protocol stack software program stored in Memory 420 and isthus performed entirely within host computer 400. Clock 490 provides asystem clock to High Speed Synthesizer 380 of FIG. 3.

[0041] In the transmit mode, true data to be transmitted is operatedupon by CPU 430, wherein the true data is wrapped with protocol data andany security data and sent to Analog Baseband & Codec 425. AnalogBaseband & Codec 425 generates the modulated baseband analog signal andsends it to RF modem 300 through Baseband to RF Interface 475. Operatorinterface 450 is a standard host operator interface but can also displayinformation concerning the operation of RF modem 300.

[0042] When wireless RF modem 300, shown in FIG. 3, is combined withhost computer 400 of FIG. 4, the same functionality as the combinationof FIG. 1 and FIG. 2 is achieved, but at a substantial reduction inparts, cost, and assembly time.

[0043] In another embodiment, the RF modem comprises an antenna and anRF head, similar to the embodiment illustrated in FIG. 3. However, inthis embodiment the RF head is configured for performing analog todigital conversion during the receive mode and digital to analogconversion during the transmit mode. Accordingly, the interface isconstructed to feed a digital signal into the host computing deviceduring the receive mode and to receive a digital signal from the hostcomputing device during the transmit mode.

[0044]FIG. 5 is a schematic illustration of a detachable wireless RFmodem 500 in accordance with another embodiment of the presentinvention, wherein the modem comprises Antenna 510, an RF head, abaseband processing unit, Clock 590 and Baseband to Host Interface 595.This embodiment is useful when it is not desirable to extensively modifythe host computer hardware but where cost savings in the RF modem canstill be realized. In this embodiment, the modem CPU function, thememory for data processing and storage, and the protocol stack controlare in the external host computer.

[0045] RF modem 500 can be constructed using standard components. Forinstance: Dual Conversion Transceiver 350 and High Speed Synthesizer 580are available from Texas Instruments of Dallas, Tex.; Analog Basebandand Codec 525 and Digital Baseband 585 are available from Analog Devicesof Norwood, Mass; and RF to Baseband Interface 595 can be any standardinterface that enables RF modem 500 to be inserted in a conventional wayinto an available slot in the host computer, i.e., Interface 595 enablesRF modem 500 to be dimensioned to fit within a cradle for a PDA orenables RF modem 500 to be dimensioned to correspond to a PCMCIApersonal computer card. Thus RF modem 500 can be designed to be housedinside the host computing device or it can be connected external to thehost computing device. Moreover, the above components of RF modem 500are electrically connected as illustrated by the solid lines in FIG. 5between those components.

[0046] RF modem 500 operates as follows. In the receive mode, Antenna510 receives an electromagnetic RF signal and forwards the RF signal toRF Switch 560. RF switch 560 may be a transmit/receive switch or aduplexer as required by the air standard. The received RF signal is thenrouted from RF switch 560 to Dual Conversion Transceiver 550 forconversion into a modulated baseband analog signal. Dual ConversionTransceiver 550 operates using various receive and transmit variablefrequency oscillator signals that are provided by High Speed Synthesizer580. Power amplifier 515 is fed the modulated RF signal from DualConversion Transceiver 550 and is fed a signal that controls poweroutput so that Power Amplifier 515 can deliver requested power to RFSwitch 560. The modulated baseband analog signal from Dual ConversionTransceiver 550 is fed into Analog Baseband and Codec 525 for properdemodulation to extract data bits having true data, which isrepresentative of the information being received, protocol bits of data,and any security coding. Digital Baseband 585 works in conjunction withan external host computer CPU and an external protocol stack softwareprogram to further process the received signal to extract the true datafrom the protocol data, remove any security coding, and send the truedata to an intended destination in the external host computer. Basebandto Host Interface 595 allows data to flow between the RF modem 500 andthe external host computer. Clock 590 provides a system clock to DigitalBaseband 585 and to High Speed Synthesizer 580.

[0047] In the transmit mode, true data to be transmitted is operatedupon by the external host CPU in cooperation with Digital Baseband 585,wherein the true data is wrapped with protocol data and any securitydata and sent to Analog Baseband & Codec 525. Analog Baseband & Codec525 generates the modulated baseband analog signal and sends it to DualConversion Transceiver 550 for conversion into an electromagnetic RFsignal. The RF signal is then amplified by the Power Amplifier 515 andsent through RF Switch 560 to Antenna 510 for transmission.

[0048] The total component count of the modem shown in FIG. 5 is lessthan the component count of a typical prior art wireless RF modem, asillustrated in FIG. 1. This represents savings in parts cost, assembly,device testing, and size.

[0049]FIG. 6 is a schematic illustration of a host computer 600 designedto work in conjunction with wireless RF modem 500 of FIG. 5. Host toBaseband Interface 695 connects with Baseband to Host Interface 595shown in FIG. 5. Host computer 600 contains a Power Source 640, a Memory620, of type ROM, RAM, SRAM, Flash, or some combination of memory types,accessible to CPU 630. Computer system I/O 660 circuitry is shownconnecting CPU 630 to Host to Baseband interface 695. Data to be sent orreceived by CPU 630 is communicated to Interface 695. Protocol data andany security code or routing code are either added to true data duringthe transmit mode or stripped from the true data during the receive modeby special protocol stack software stored in Memory 620 and executed bythe CPU 630. Standard software drivers are used for a connection usingstandard AT Modem commands. Operator interface 650 can be programmed todisplay information concerning the operation of RF modem 500. Whenwireless RF modem 500 is combined with host computer 600 and appropriatesoftware, a reduction in cost over the prior art is realized becausewireless communications are performed using only one CPU and one memory.

[0050]FIG. 7 is a schematic illustration of a system for wireless datacommunications in accordance with another embodiment of the presentinvention comprising the wireless RF modem of FIG. 3 equipped with an RFidentification (“RFID”) unit 710 and the host computer of FIG. 4modified with RFID software that is added to Memory 420 and executed byCPU 430.

[0051] RFID 710 is powered by a Power Source 440. When power is firstapplied, RFID 710 preferably generates an analog tone identificationsignal to identify one or more predetermined characteristics of the RFhead. The identification signal is coupled to the host computer 750 viaRF to Baseband Interface 375. RFID software in host computer 750programs Analog Baseband & Codec 425 to detect and decode the analogtone generated by RFID 710 during startup. Based upon the detectedcharacteristics of the RF head contained in the signal from the RFID710, CPU 430 configures Analog Baseband & Codec 425, Clock 490, HighSpeed Synthesizer 380, and Dual Conversion Transceiver 350 to transmitand receive at a desired standard and frequency under use, such as GSMat 1900 MHz, GSM at 1800 MHZ, CDMA at 1800 MHZ, etc. The identificationsignal from RFID unit 710 may also be a multi-tone or a signal tone atdiscrete frequencies, or the like. The identification signal may also bea digital signal generated by RFID unit 710. After CPU 430 configures RFmodem 700, the RFID tones are disabled until the unit power is cycled onagain.

[0052] In another embodiment of the present invention, the identicalRFID 710 hardware and the accompanying software stored in the hostcomputer memory and executed by the host CPU is be used with RF modem500 shown in FIG. 5 in combination with host computer 600 shown in FIG.6.

[0053]FIG. 8 is a flow chart illustrating the steps taken by the systemof FIG. 7, wherein a host computer identifies an RFID identificationsignal emitted by an RFID unit. In step 810, the host computer powersup, initializes host computer circuitry and software to look for atleast one RFID tone and sets the host computer to periodically interruptits operation to look for at least one different or new RFID tone. RFmodem enabled is set to FALSE. In step 820, the presence of at least oneRFID tone is tested for. If at least one RFID tone is found, the hostcomputer CPU, at step 830, decodes the tone or tones and programs thehardware to an air standard and frequency compatible with the RF headand sets the RF modem to the detected air standard and sets RF modemenabled to TRUE. After these setup steps, the host computer CPUcommences normal operation at step 840. The host computer's operation isoccasionally interrupted to search for at least one different or newRFID tone indicating that a new or different RF head was in place. If anRFID tone is not detected in step 820, the host computer CPU continueson with normal operation in step 840.

[0054] In addition to the embodiments of the present inventionillustrated above, the present invention may be practiced in many otherways, i.e., a direct conversion transceiver could be used in place ofthe dual conversion transceiver illustrated and Superhetrodyne orsub-sampling analog to baseband solutions may be used.

[0055] The embodiments of the distributed architecture wireless RF modemdescribed above are illustrative of the principles of the presentinvention and are not intended to limit the invention to the particularembodiments described. Other embodiments of the present invention can beadapted for use in any RF wireless environment. Accordingly, while thepreferred embodiment of the invention has been illustrated anddescribed, it will be appreciated that various changes can be madetherein without departing from the spirit and scope of the invention.

What is claimed is:
 1. A detachable wireless radio frequency (RF) modemconstructed to cooperatively operate with a host computing device havinga memory, a central processing unit (“CPU”) for executing a protocolstack software program stored in said memory, and a baseband processingunit, said RF modem comprising: an antenna; an RF head coupled to saidantenna and configured during a receive mode to receive anelectromagnetic RF signal through said antenna and to convert said RFsignal into a modulated baseband analog signal for baseband processingin said host computing device, said RF head further configured during atransmit mode to receive a modulated baseband analog signal generated bysaid host computing device and to convert said modulated baseband analogsignal into an electromagnetic RF signal to feed to said antenna; and aninterface coupled to said RF head and configured to physically couplesaid RF modem to said host computing device, said interface furtherconfigured during said receive mode to feed said modulated basebandanalog signal generated by said RF head to said host computing device,such that said baseband processing unit is enabled to convert saidmodulated baseband analog signal into a plurality of bits of dataincluding protocol data and true data, and said CPU operating under thecontrol of said protocol stack software program is enabled to separatesaid protocol data from said true data, said interface furtherconfigured during said transmit mode to feed said modulated basebandanalog signal generated by said host computing device to said RF head.2. The RF modem of claim 1 wherein said RF head has at least onepredetermined operating characteristic and wherein said RF modem furthercomprises an RF identification unit (“RFID”) coupled between said RFhead and said interface, said RFID operative to generate anidentification signal that identifies said at least one operatingcharacteristic of said RF head, said interface configured to feed saididentification signal to said host computing device such that said hostcomputing device is enabled to detect said identification signal anddecode said at least one operating characteristic.
 3. The RF modem ofclaim 2, wherein said identification signal is an analog tone.
 4. The RFmodem of claim 2, wherein said identification signal is a digitalsignal.
 5. The RF modem of claim 2, wherein one said operatingcharacteristic of said RF head is an air standard used by said RF head.6. The RF modem of claim 2, wherein one said operating characteristic ofsaid RF head is a frequency under which said RF head can operate.
 7. TheRF modem of claim 1, wherein said host computing device is a personaldigital assistant.
 8. The RF modem of claim 7, wherein said RF modem isdimensioned to fit within a cradle for a personal digital assistant. 9.The RF modem of claim 1, wherein said host computing system is a laptopcomputer.
 10. The RF modem of claim 9, wherein said RF modem isdimensioned to correspond to a PCMCIA personal computer card.
 11. The RFmodem of claim 1, wherein said interface is located internal to saidhost computing device.
 12. The RF modem of claim 1, wherein saidinterface is located external to said host computing device.
 13. Asystem for providing wireless data communications comprising: (a) adetachable wireless radio frequency (RF) modem comprising: (1) anantenna; (2) an RF head coupled to said antenna, said RF head configuredduring a receive mode to receive an electromagnetic RF signal throughsaid antenna and to convert said electromagnetic signal into a modulatedbaseband analog signal, said RF head further configured during atransmit mode to receive an externally generated modulated basebandanalog signal and to convert said modulated baseband analog signal intoan electromagnetic signal to feed to said antenna; and (3) an interfacecoupled to said RF head; and (b) a host computing device physicallycoupled to said RF modem via said interface, said host computing deviceconfigured during said receive mode to receive said modulated basebandanalog generated by said RF head through said interface, to convert saidmodulated baseband analog signal into a plurality of bits of dataincluding protocol data and true data, and to separate said protocoldata from said true data, said host computing device further configuredduring said transmit mode to generate said modulated baseband analogsignal for feeding to said RF head through said interface.
 14. Thesystem of claim 13, wherein said RF head has at least one predeterminedoperating characteristic and wherein said RF modem further comprises anRF identification unit (“RFID”) coupled between said RF head and saidinterface, said RFID operative to generate an identification signal thatidentifies said at least one operating characteristic of said RF head,said interface configured to feed said identification signal to saidhost computing device such that said host computing device is enabled todetect said identification signal and decode said at least one operatingcharacteristic.
 15. A detachable wireless radio frequency (RF) modemconstructed to cooperatively operate with a host computing device havinga memory and a central processing unit (“CPU”) for executing a protocolstack software program stored in said memory, said RF modem comprising:an antenna; an RF head coupled to said antenna, said RF head configuredduring a receive mode to receive an electromagnetic RF signal throughsaid antenna and to convert said electromagnetic signal into a modulatedbaseband analog signal, said RF head further configured during atransmit mode to receive said modulated baseband analog signal and toconvert said modulated baseband analog signal into said electromagneticsignal to feed to said antenna; a baseband processing unit coupled tosaid RF head, said baseband processing unit configured during saidreceive mode to convert said modulated baseband analog signal into aplurality of bits of data including protocol data and true data, suchthat said CPU operating under the control of said protocol stacksoftware program is enabled to separate said protocol data from saidtrue data, said baseband processing unit further configured during saidtransmit mode to convert said plurality of bits of data including saidprotocol data and said true data into said modulated baseband analogsignal; and an interface coupled to said baseband processing unit andconfigured to physically couple said RF modem to said host computingdevice.
 16. The RF modem of claim 15 wherein said RF head has at leastone predetermined operating characteristic and wherein said RF modemfurther comprises an RF identification unit (“RFID”) coupled betweensaid RF head and said interface, said RFID operative to generate anidentification signal that identifies said at least one operatingcharacteristic of said RF head, said interface configured to feed saididentification signal to said host computing device such that said hostcomputing device is enabled to detect said identification signal anddecode said at least one operating characteristic.
 17. A system forproviding wireless data communications comprising: (a) a detachablewireless radio frequency (RF) modem comprising: (1) an antenna; (2) anRF head coupled to said antenna, said RF head configured during areceive mode to receive an electromagnetic RF signal through saidantenna and to convert said electromagnetic signal into a modulatedbaseband analog signal, said RF head further configured during atransmit mode to receive said modulated baseband analog signal and toconvert said modulated baseband analog signal into said electromagneticsignal to feed to said antenna; (3) a baseband processing unit coupledto said RF head, said baseband processing unit configured during saidreceive mode to convert said modulated baseband analog signal into aplurality of bits of data including protocol data and true data, saidbaseband processing unit further configured during said transmit mode toconvert said plurality of bits of data including said protocol data andsaid true data into said modulated baseband analog signal; and (4) aninterface coupled to said baseband processing unit; and (b) a hostcomputing device physically coupled to said RF modem via said interface,said host computing device configured during said receive mode toseparate said protocol data from said true data, said host computingdevice further configured during said transmit mode to combine saidprotocol data with said true data.
 18. The system of claim 17, whereinsaid RF head has at least one predetermined operating characteristic andwherein said RF modem further comprises an RF identification unit(“RFID”) coupled between said RF head and said interface, said RFIDoperative to generate an identification signal that identifies said atleast one operating characteristic of said RF head, said interfaceconfigured to feed said identification signal to said host computingdevice such that said host computing device is enabled to detect saididentification signal and decode said at least one operatingcharacteristic.
 19. A detachable wireless radio frequency (RF) modemhaving at least one predetermined operating characteristic andconstructed to cooperatively operate with a host computing device, saidhost computing device having a memory, a central processing unit (“CPU”)for executing a protocol stack software program stored in said memory,and a baseband processing unit, said RF modem comprising: an antenna; anRF head configured during a receive mode to receive an electromagneticRF signal through said antenna coupled to said RF head and to convertsaid electromagnetic signal into a modulated baseband analog signal forbaseband processing in said host computing device, said RF head furtherconfigured during a transmit mode to receive a modulated baseband analogsignal generated by said host computing device and to convert saidmodulated baseband analog signal into an electromagnetic signal to feedto said antenna; an interface coupled to said RF head and configured tophysically couple said RF modem to said host computing device, saidinterface further configured during said receive mode to feed saidmodulated baseband analog signal generated by said RF head to said hostcomputing device, such that said baseband processing unit is enabled toconvert said modulated baseband analog signal into a plurality of bitsof data including protocol data and true data, and said CPU operatingunder the control of said protocol stack software program is enabled toseparate said protocol data from said true data, said interface furtherconfigured during said transmit mode to feed said modulated basebandanalog signal generated by said host computing device to said RF head;and an RF identification unit (“RFID”) coupled between said RF head andsaid interface, said RFID operative to generate an identification signalthat identifies said at least one operating characteristic of said RFhead, said interface configured to feed said identification signal tosaid host computing device such that said host computing device isenabled to detect said identification signal and decode said at leastone operating characteristic.
 20. A detachable wireless radio frequency(RF) modem having at least one predetermined operating characteristicand constructed to cooperatively operate with a host computing devicehaving a memory and a central processing unit (“CPU”) for executing aprotocol stack software program stored in said memory, said RF modemcomprising: an antenna; an RF head coupled to said antenna, said RF headconfigured during a receive mode to receive an electromagnetic RF signalthrough said antenna and to convert said electromagnetic signal into amodulated baseband analog signal, said RF head further configured duringa transmit mode to receive said modulated baseband analog signal and toconvert said modulated baseband analog signal into said electromagneticsignal to feed to said antenna; a baseband processing unit coupled tosaid RF head, said baseband processing unit configured during saidreceive mode to convert said modulated baseband analog signal into aplurality of bits of data including protocol data and true data, suchthat said CPU operating under the control of said protocol stacksoftware program is enabled to separate said protocol data from saidtrue data, said baseband processing unit further configured during saidtransmit mode to convert said plurality of bits of data including saidprotocol data and said true data into said modulated baseband analogsignal; an interface coupled to said baseband processing unit andconfigured to physically couple said RF modem to said host computingdevice; and an RF identification unit (“RFID”) coupled between said RFhead and said interface, said RFID operative to generate anidentification signal that identifies said at least one characteristicof said RF head, said interface configured to feed said identificationsignal to said host computing device such that said host computingdevice is enabled to detect said identification signal and decode saidat least one operating characteristic.
 21. A method for wireless datacommunications in a system comprising a detachable wireless radiofrequency (“RF”) modem having an RF head and an interface, said RF modemconstructed to cooperatively work with and be physically coupled at saidinterface to a host computing device, said host computing device havinga memory, a central processing unit (“CPU”) for executing a protocolstack software program stored in said memory and a baseband processingunit, said method comprising: (a) receiving by said system an RFelectromagnetic signal having information to be received, said receivingcomprising: (1) receiving in said RF head said electromagnetic signal;(2) converting by said RF head said electromagnetic signal into amodulated baseband analog signal; (3) feeding by said RF modem throughsaid interface said modulated baseband analog signal into said hostcomputing device; (4) converting by said baseband processing unit saidmodulated baseband analog signal into a plurality of bits of dataincluding protocol data and true data; (5) separating said protocol datafrom said true by said CPU operating under the control of said protocolstack software program; and (b) transmitting by said system anelectromagnetic RF signal having information to be sent, saidtransmitting comprising: (1) generating by said baseband processing unita modulated baseband analog signal from said plurality of bits of dataincluding said protocol data and said true data, said plurality of databits representing said information to be sent; (2) feeding by said hostcomputer through said interface said modulated baseband analog signalinto said RF modem; (3) converting by said RF head said modulatedbaseband analog signal into said electromagnetic signal havinginformation being sent.
 22. A method for wireless data communications ina system comprising a detachable wireless radio frequency (“RF”) modemhaving an RF head, a baseband processing unit and an interface, said RFmodem constructed to cooperatively work with and be physically coupledat said interface to a host computing device, said host computing devicehaving a memory and a central processing unit (“CPU”) for executing aprotocol stack software program stored in said memory, said methodcomprising: (a) receiving by said system an electromagnetic RF signalhaving information to be received, said receiving comprising: (1)receiving in said RF head said electromagnetic signal; (2) converting bysaid RF head said electromagnetic signal into a modulated basebandanalog signal; (3) converting by said baseband processing unit saidmodulated baseband analog signal into a plurality of bits of dataincluding protocol data and true data; (4) separating said protocol datafrom said true data by said CPU operating under the control of saidprotocol stack software program; and (b) transmitting by said system anelectromagnetic RF signal having information to be sent, saidtransmitting comprising: (1) generating by said CPU said plurality ofdata bits including said protocol data and said true data, saidplurality of data bits representing said information to be sent; (2)generating by said baseband processing unit a modulated baseband analogsignal from said plurality of bits of data bits including said protocoldata and said true data; (3) converting by said RF head said modulatedbaseband analog signal into said electromagnetic signal havinginformation being sent.
 23. A method for detecting an identificationsignal in a system comprising a wireless radio frequency (“RF”) modemhaving an RF head with at least one predetermined operatingcharacteristic and a radio frequency identification (“RFID”) unit forgenerating an identification signal that identifies said at least oneoperating characteristic of said RF head, said system further comprisinga host computing device physically connected to said modem and having, apower supply, memory and a central processing unit (“CPU”) for executingRFID software stored in said memory, said method comprising: (a)powering up said host computing device and initializing said hostcomputing device to detect said identification signal; (b) setting saidhost computing device to periodically interrupt its operation to detectfor a different identification signal; (c) setting said modem enabled toFALSE; (d) detecting for the presence of said identification signal, andif said identification signal is detected: (1) decoding saididentification signal to determine said at least one characteristic ofsaid RF head; (2) programming said modem and said host computing deviceaccording to said characteristics of said RF head; and (3) setting saidmodem enabled to TRUE; and (e) performing normal operations by said CPUand setting said host computing device to periodically interrupt itsoperation to detect for a different identification signal.
 24. Adetachable wireless radio frequency (RF) modem constructed tocooperatively operate with a host computing device having a memory, acentral processing unit (“CPU”) for executing a protocol stack softwareprogram stored in said memory, and a baseband processing unit, said RFmodem comprising: an antenna; an RF head coupled to said antenna andconfigured during a receive mode to receive an electromagnetic RF signalthrough said antenna, to convert said RF signal into a modulatedbaseband analog signal and to perform digital to analog conversion ofsaid RF signal to enable said host computing device to perform abaseband processing function, said RF head further configured during atransmit mode to receive a digital signal generated by said hostcomputing device and to convert said digital signal into anelectromagnetic RF signal to feed to said antenna; and an interfacecoupled to said RF head and configured to physically couple said RFmodem to said host computing device, said interface further configuredduring said receive mode to feed said digital signal generated by saidRF head to said host computing device, to enable said basebandprocessing unit to perform said baseband processing function and toenable said CPU operating under the control of said protocol stacksoftware program to separate protocol data from true data, saidinterface further configured during said transmit mode to feed saiddigital signal generated by said host computing device to said RF head.